The present invention concerns a coupling for releasably connecting a movable furniture part to a drive, comprising a first coupling portion for fastening to the movable furniture part and a second coupling portion for fastening to the drive. The first coupling portion has an opening for at least partially receiving the second coupling portion.
Couplings of that kind suffer from the problem that, by virtue of installation tolerances in respect of the drive or the movable furniture part in the body or carcass of the piece of furniture, it is not always possible to predict how far the second coupling portion can be introduced into the opening in the first coupling portion. Thus, for example, the drive or the movable furniture part (and therewith the corresponding coupling portions) can be disposed at differing depths in the furniture body or carcass, depending on the respective installation situation.
The object of the invention is to develop a coupling of the general kind set forth, such that it involves compensation at least in respect of the depth tolerance in relation to the arrangement of the first and second coupling portions.
That object is obtained by a coupling having the feature of the present invention.
The provision of a locking mechanism which ensures locking of the two coupling portions relative to each other for different depths of insertion of the second coupling portion into the first coupling portion achieves the depth tolerance compensation required in accordance with the statement of object.
In a preferred embodiment of the coupling, it is provided that the locking mechanism releases the connection between the first and second coupling portions upon the attainment of a predetermined separation force. In that case, it is desirable if the predetermined separation force is of equal magnitude for the at least two different positions. That provides that use of the coupling does not involve any noticeable dependencies on the actual installation position.
The locking mechanism can have, for example, two clamping jaws which are biased relative to each other by a force storage means (for example springs) and which clamp the second coupling portion fast in the locking condition. If the separation force acting on the two coupling portions exceeds the force exerted on the clamping jaws by the force storage means, the locking mechanism is opened. That leads to uncoupling of the drive and the movable furniture part.
To facilitate insertion of the second coupling portion into the opening in the first coupling portion, a pin for insertion into the opening can be arranged on the second coupling portion. In that case, the pin can have at least two axially mutually spaced latching positions for the clamping jaws.
The two mutually spaced latching positions allow locking of the two coupling portions in the two different positions of the first and second coupling portions relative to each other.
In that case, each of the latching positions can have at least one groove, into which the clamping jaws engage in the locking condition.
There can also be two or more grooves per latching position so that the clamping jaws engage into two or more grooves in each latching position.
If the separation force for the at least two different positions of the coupling portions is to be of the same magnitude, it must however be guaranteed that the number of grooves into which the clamping jaws engage in the locking condition is the same for each of the latching positions.
It can be provided that the latching positions are markedly spaced from each other over the axial extent of the pin. Therefore, there is a non-grooved axial region of the pin between the grooves of the respective latching positions. It will be noted, however, that this is disadvantageous insofar as that only affords a stepwise compensating option for depthwise positioning of the two coupling portions relative to each other.
It is therefore particularly preferably provided that the pin has a plurality of adjacent grooves over its axial extent. In this case, therefore, there are non-grooved intermediate spaces between the individual latching positions. If it is provided that the clamping jaws respectively engage into a groove in the locking condition, a dedicated latching position is implemented by each groove. That affords an approximately stepless compensating option, in relation to the depthwise tolerance.
In order to permit the pin to be captured in a direction at a right angle to the direction of insertion (that is to say in the case of an eccentric approach), a funnel can be arranged in front of the opening of the first coupling portion.
The coupling according to the invention is suitable for a wide range of different drives. It will be noted, however, that it is particularly preferable that the second coupling portion is connectable to the pulling means (pulling member) of a retraction device.
The present invention further concerns a retraction device for a movable furniture part having a pulling means which can be wound on a roller, and there is provided an electric motor for driving the roller. The retraction device is distinguished by a second coupling portion, connected to the pulling means, of a coupling in accordance with one of the aforementioned embodiments.
Such a refraction device can be provided with a housing, in which the roller and the electric motor are arranged. In that case, it is advantageous if the housing has in the unwinding region of the roller a window which is substantially larger than the cross-section of the pulling means. As a result, the pulling means can relatively freely move in the unwinding region in a direction in an orthogonal relationship to the unwinding direction (and thus in an orthogonal relationship to the direction of movement of the movable furniture part), which provides for compensation in relation to installation tolerances at a right angle to the unwinding direction.
For example the diameter of the pulling means can be between about 0.5 mm and 1 mm, while the window is of a length and a width of about 5 mm.
If the retraction device is to have a touch-latch functionality (in that case the roller is releasable by an externally applied force acting on the movable furniture part) or if the intention is to ensure that, when a coupling is in an unlocked condition, the pulling means is wound on to the roller, the roller can be biased in the winding direction by a force storage means.
The force storage means serves on the one hand to wind on the pulling means when the coupling is unlocked. On the other hand, the force storage means provides for mechanical tension along the pulling means. By virtue of that arrangement, forces exerted on the movable furniture part by a user can be transmitted to the roller by way of the pulling means. A pulling or pushing force applied to the movable furniture part thereby results in a certain rotary movement of the roller, which can be detected by a suitable sensor (for example a rotary potentiometer). The sensor then triggers the electric motor of the retraction device (touch-latch functionality).